Environmental Science: Nano最新文献

Ethyl cyanoacrylate nanoparticles (ECA-NPs) have recently been reported as promising novel antibacterial NPs capable of inhibiting the growth of several Gram-positive and Gram-negative bacteria. However, the effects of ECA-NPs on microalgae, which are primary producers in aquatic ecosystems, remain unknown. In this study, we examined the effects of ECA-NPs on the microalga Chlorella vulgaris (Chlorella) at both cellular and molecular levels. A high concentration of ECA-NPs (100 μg mL⁻¹) exhibited strong growth inhibitory effects on Chlorella. In the ECA-NP-treated cells, transmission electron microscope (TEM) observations showed the prominent internalization of ECA-NPs in the periplasmic space and vacuoles. Moreover, notable morphological changes such as a thinner cell wall, stacked thylakoid structure, and plasmolysis were observed. ECA-NP exposed Chlorella secreted more extracellular polymeric substances (EPS) and accumulated more storage lipids (mainly triacylglycerol, TAG) compared to the control. However, the contents of total fatty acids and starch were decreased, and photosynthetic activity was reduced. In addition, the content of intracellular reactive oxygen species (ROS) and the activities of antioxidant enzymes in ECA-NP-treated cells were significantly higher than those in the control. Transcriptomic analysis revealed the downregulation of genes that are involved in the drug binding/catabolic process, chemical stimulus detection, and cell wall component catabolic process (chitin catabolism), while genes involved in the photosynthetic membrane and plastid thylakoid were upregulated. These results indicated that the effects of ECA-NP exposure are not limited to specific metabolic pathways, but rather influence metabolic pathways across the entire cell. This study also provided new insights into the potential toxic effects associated with cyanoacrylate NPs in phytoplankton.

This review explores the advancements and trends in biologically synthesized Fe⁰-based nanoparticles (NPs) and their applications as catalysts in treating chlorinated organic compounds. The persistent nature and bioaccumulative characteristics of chlorinated organic compounds enable their accumulation in water, soil, and the food chain, leading to significant environmental and human health issues. The widespread presence of these toxic substances underscores the urgent need for effective treatment and remediation strategies. Biologically synthesized Fe⁰-based NPs are recognized for their considerable surface area, potent reduction properties, and environmental compatibility. These attributes render them a promising approach for the remediation of chlorinated compounds. This review categorizes synthesis methods into key groups: microorganisms, plant extracts, biological waste, and industrial–agricultural by-products. Recent studies highlight the promising applications of bio-NPs in environmental remediation, emphasizing their potential for sustainable and efficient treatment solutions. This analysis thoroughly examines current trends in the application and enhancement of nanoparticle activity, delineating various challenges and future prospects comprehensively. It offers well-defined research directions with high practical relevance, aiming to contribute to advancing knowledge and guiding future research endeavors in the field.

Inferring from our experience so far with the International Space Station, deep space missions are bound to encounter new challenges in life support systems, including water supply. The complexity of these missions might demand spacecraft and facilities to be uncrewed for several months. In this situation, biofilm growth can deteriorate the quality of stored water, leading to failure of water supply system during reinitiation and thus threatening the success of such missions. Antimicrobial coatings have been used for biofilm mitigation under various conditions. A successful coating to control biofilm formation in deep space missions, must have a long lifetime considering the duration of such missions. In this study, a solution to the short lifetime of silver nanoparticles as an antimicrobial coating is provided. Passivation with sulfide was performed to control the release of silver ions from silver nanoparticles, thereby prolonging the antimicrobial activity. Stainless steel bellow pieces, as the most prone parts to biofilm growth, were chosen as the substrate. The pieces were coated with silver and passivated silver at different passivation degrees to find the optimum condition. The substrates were exposed to Pseudomonas aeruginosa in an M9 medium for 12 months for the biofilm formation. The bacteria count on the bellow pieces as a representative of the biofilm as well as the bacteria count and silver ion concentration in the M9 medium were measured at 1.5, 3, 6, and 12 month time points. It was observed that passivation slowed down the silver ion release rate from silver nanoparticles. However, biofilm mitigation at the end of the experiment for one passivated coating was the same as that of the silver coating, which means that the passivated coating can last longer by releasing less amount of silver ions, which are the antimicrobial agents. Besides investigating the performance in biofilm mitigation, we demonstrate that the bellows can be coated homogeneously in a continuous reactor and passivation can enhance the stability of the coating to mechanical stress during expansion/retraction of the bellow, paving the way for the application of the passivated silver coating for space missions.

Graphene oxide (GO) and graphene oxide–gold (GO–Au) nanohybrids offer promising applications in nanomedicine, biosensing, and environmental technology due to their unique properties. However, concerns regarding their environmental and biological safety remain largely unexplored. This study, using a safe and sustainable by design (SSbD) approach, evaluates the cytotoxicity, oxidative stress, and dispersion stability of GO and GO–Au nanohybrids in zebrafish ZF4 cells. GO was synthesised using a modified Hummer's method and GO–Au nanohybrids were prepared by incorporating gold nanoparticles (AuNPs) into the GO matrix. Physicochemical characterisation revealed enhanced dispersion stability of GO–Au nanohybrids, retaining over 98% of their initial absorbance in ultrapure water (UPW) and over 95% in DMEM/F12 after 48 hours. In contrast, GO displayed higher levels of sedimentation. Toxicity assessments indicated a dose- and time-dependent decrease in cell viability. After 72 hours, ZF4 cell viability was reduced to 39.5% for 150 μg mL⁻¹ GO, whereas GO–Au treatment at the same concentration exhibited a less severe reduction (54.5% viability). Reactive oxygen species (ROS) generation was significantly higher in GO-treated cells compared to GO–Au, with GO generating approximately 2x more ROS at concentrations of 50 μg mL⁻¹ and 100 μg mL⁻¹. Apoptosis and necrosis rates were also significantly elevated in GO-treated cells, with necrosis reaching 53.1% at 100 μg mL⁻¹, compared to 14.6% in GO–Au-treated cells. These findings demonstrate that the incorporation of AuNPs reduces cytotoxicity and oxidative stress by enhancing the colloidal stability of GO–Au nanohybrids. This study provides critical baseline data on the interaction of GO-based nanomaterials (NMs) with biological systems and highlights the importance of NM modification for safer, more sustainable applications.

The interaction between per- and polyfluoroalkyl substances (PFASs) and nanoplastics (NPLs) in the environment is a growing concern due to their possible combined toxicity and potential impacts on ecosystems and human health. In aqueous compartments, their common migration strongly depends on the colloidal stability of the particles. Here, a clear relation between the toxicity and aggregation stage of colloids containing positively charged polystyrene NPLs and PFAS perfluorohexanoic acid (PFHxA) was established. PFHxA adsorption on NPLs altered the particle charge leading to unstable dispersions at the charge neutralization point and stable ones away from this condition. Toxicity studies on zebrafish embryos shed light on the synergistic mortality effect of the NPL–PFHxA adducts, and such a synergy strengthened with the increase in the dispersion stability highlighting the importance of environmental conditions like the NPL-to-PFAS ratio. The findings unambiguously demonstrate that high colloidal stability of environmental samples polluted with both NPLs and PFAS leads to remarkable synergistic toxicity on living ecosystems, while the individual particles are expected to migrate faster in the environment than their aggregated counterparts.

Interfacial chemical bonding is essential for speeding up the separation and transfer of charge carriers at the heterojunction interface, thereby improving the photocatalytic activity. Herein, two-dimensional ZnFe₂O₄ nanosheets were grown in situ on Bi-MOF nanorods by a facile hydrothermal method, creating Bi-MOF/ZnFe₂O₄ heterojunctions with interfacial Bi–O–Zn bonds. The optimized sample (ZFB-2) exhibited significantly higher photocatalytic degradation efficiency of tetracycline hydrochloride (TC), which was 41.7 times and 2.0 times that of Bi-MOF and ZnFe₂O₄, respectively. Furthermore, ZFB-2 exhibited notable stability, demonstrating no obvious reduction in TC removal across five cyclic experiments, while also retaining its interfacial Bi–O–Zn bonds and morphology. The interfacial Bi–O–Zn bonds not only boosted the light absorption of ZFB-2 but also expedited the transfer of charge carriers via an S-scheme charge transfer pathway, functioning as conduits for charge transfer. It was found that h⁺ and ·O₂⁻ were the dominating active species, and the coexisting ions had a negligible effect on photocatalytic degradation of TC over ZFB-2. The potential degradation routes for tetracycline were outlined, and the toxicity of the resulting intermediates was assessed. This study offers a deep understanding of interfacial modulation of MOF-based S-scheme heterojunction photocatalysts and their enhanced performances in wastewater treatment for antibiotic removal.

About 13.7 million people died worldwide from infectious diseases in 2019, which accounts for one fifth of all annual deaths. Infectious diseases are caused by microbes (i.e. bacteria, fungi, viruses) predominantly targeting the respiratory system, bloodstream, gastrointestinal region and urinary tract, which can lead to severe health problems. Microbes can naturally adapt and develop antimicrobial resistance to conventional medication. Health systems are concerned by the overuse of antibiotics in the medical, agricultural, and food industries. This leads to bacterial multidrug resistance, causing more than half a million deaths annually. In consequence, research and innovation have focused on nano-scaled advanced materials to explore their potential to reinforce antimicrobial treatments. Advanced materials are complex composites that achieve superior, combined functionalities with an optimized safety, sustainability, and circularity profile. They often contain nano-scaled materials, which are highly versatile, organic, or inorganic materials that can adopt different sizes, compositions, topographies, and surface modifications. All these properties need to be carefully defined using physicochemical characterization techniques and should be considered when selecting the most efficient nanomaterials against widespread microbes. In this review, we cover (i) potential candidates of engineered nanomaterials and their physicochemical characteristics, and demonstrate their efficacy in antimicrobial action; (ii) the mechanisms of action against microbes specific to nanomaterials; (iii) well-established methods and highlight methodological advancements; (iv) the potential improvements in sustainability and circularity; (v) the current and future fields of application and ongoing development in the medical, agricultural, high-tech, textile, and food industries. For the first time, nano-scaled advanced materials produced by green synthesis methods are discussed with respect to their gain in sustainability and circularity and a comprehensive set of methodologies for safety, sustainability, and circularity assessment are described in detail.

In this work, a simple hydrothermal process was utilized for preparing ErVO₄ nanoparticles. The prepared ErVO₄ nanoparticles were used for the electrochemical detection of hazardous 4-nitrotoluene. The physicochemical properties of ErVO₄ nanoparticles were examined using various characterization techniques, including X-ray diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. Using differential pulse voltammetry (DPV) and cyclic voltammetry (CV), the electrochemical detection of 4-nitrotoluene was assessed. In the 0.01–375 μM detection range, the ErVO₄ modified screen-printed carbon electrode (SPCE) sensor showed a low detection limit of 9 nM. The constructed ErVO₄/SPCE sensor exhibits selective detection in the presence of other chemical species, reproducibility, reusability, and real sample validation with a recovery range of ±95.00–99.00%. Compared to several previously reported sensors, ErVO₄ gave a substantially lower LOD for 4-nitrotoluene detection and was easier and faster to fabricate. The proposed ErVO₄-modified electrochemical sensor for 4-nitrotoluene described is affordable and flexible, enabling point-of-care 4-nitrotoluene testing essential for successful environmental monitoring and water quality accreditation.

The production of sulfur by catalytically reducing SO₂ with CO presents a promising approach for utilizing sulfur oxides found in flue gases. While the novel desulfurization technique exhibits commendable attributes such as heightened efficacy and economical feasibility, its progression is hampered by challenges of catalyst poisoning-induced service life constraints. In this work, the optimization of the Gd@CeO_x catalyst prepared by a hydrothermal process aimed to enhance its resistance to poisoning. The results reveal that the catalyst achieved a conversion of 71.6% and a sulfur yield of 64.6% after a 72 h reaction at 400 °C. This notable performance is ascribed to the hydrothermal synthesis of more porous structures, which improve gas adsorption and activation, as well as increase the presence of alkali on the surface of the Gd@CeO_x catalyst. The reaction mechanism follows both L–H and E–R pathways. This work offers a cost-effective and efficient approach to flue gas desulfurization, with substantial implications for sulfur resource utilization.